Exterior entry doors have traditionally been fabricated from wood. Although wood provides a very satisfying aesthetic appearance, it is prone to rotting; cracking, and splitting. Additionally, wood is expensive and is considered a limited natural resource. For these reasons, the door industry has looked to other materials for fabricating doors. Composite materials are sometimes selected in lieu of natural wood for entry door production. Generally, such doors comprise first and second door facings spaced apart from and parallel to one another. The door facings may be substantially planar, or contoured to include panels and the like. Various techniques are known for providing the door facings with contours and decorative appearances.
The molded door facings are secured to a frame positioned between the facings. The frame typically comprises upper and lower rails at the top and bottom of the door facings, and stiles at the opposite sides of the door facings. The rails and stiles are preferably selected to provide an aesthetic appearance matching that of the door facings. Also, the physical properties of the rails and stiles and other components selected preferably are compatible with the intended uses and environment of the door. For example, a stile is typically used for hinge-mounting a door to a doorjamb. Accordingly, the stile should possess physical properties, such as screw retention properties, consistent with this and other intended uses.
Fiberglass composite door facings were developed as an improvement over traditional wood doors, and resist rotting, cracking and splitting. Although such doors include door facings formed from fiberglass, their stiles and rails are typically formed from solid wood. Wood rails, stiles, and other components exposed to the environment suffer from the same drawbacks mentioned above with respect to traditional wood doors, including rotting, cracking, and splitting.
Conventional polymer rails, stiles, and other door components have been proposed, but often lack the aesthetic and physical properties of wood, exhibit inferior paintability characteristics, and possess poor screw retention. Further, such components are expensive and often have unsatisfactory expansion characteristics. For these reasons, some conventional polymeric stiles have not proven commercial viable.
Other designs provide for edge inserts formed from a relatively inexpensive plastic, such as polystyrene, which are mechanically joined to the door frame. However, the plastic used in such designs tends to melt during door trimming and cutting operations, and therefore has also not proven to be a commercially viable option for many door manufacturing processes.
Still other designs use polymer composites having a relatively high amount of filler materials in order to reduce costs. However, the resulting door stiles formed from such composites are too hard to machine during door processing, and thus have also not proven to be an acceptable design. In addition, the resulting exteriorly exposed surface along the door edges of such designs is often not acceptable in the market.